/*
 * Copyright (c) 2005-2017 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <asn_system.h>
#include <asn_internal.h>
#include <asn_bit_data.h>

/*
 * Create a contiguous non-refillable bit data structure.
 * Can be freed by FREEMEM().
 */
asn_bit_data_t* asn_bit_data_new_contiguous(
    const void* data, size_t size_bits) {
  size_t size_bytes = (size_bits + 7) / 8;
  asn_bit_data_t* pd;
  uint8_t* bytes;

  /* Get the extensions map */
  pd = CALLOC(1, sizeof(*pd) + size_bytes + 1);
  if (!pd) {
    return NULL;
  }
  bytes = (void*) (((char*) pd) + sizeof(*pd));
  memcpy(bytes, data, size_bytes);
  bytes[size_bytes] = 0;
  pd->buffer        = bytes;
  pd->nboff         = 0;
  pd->nbits         = size_bits;

  return pd;
}

char* asn_bit_data_string(asn_bit_data_t* pd) {
  static char buf[2][32];
  static int n;
  n = (n + 1) % 2;
  snprintf(
      buf[n], sizeof(buf[n]),
      "{m=%" ASN_PRI_SIZE " span %" ASN_PRI_SIZE "[%" ASN_PRI_SIZE
      "..%" ASN_PRI_SIZE "] (%" ASN_PRI_SIZE ")}",
      pd->moved, ((uintptr_t)(pd->buffer) & 0xf), pd->nboff, pd->nbits,
      pd->nbits - pd->nboff);
  return buf[n];
}

void asn_get_undo(asn_bit_data_t* pd, int nbits) {
  if ((ssize_t) pd->nboff < nbits) {
    assert((ssize_t) pd->nboff < nbits);
  } else {
    pd->nboff -= nbits;
    pd->moved -= nbits;
  }
}

/*
 * Extract a small number of bits (<= 31) from the specified PER data pointer.
 */
int32_t asn_get_few_bits(asn_bit_data_t* pd, int nbits) {
  size_t off;    /* Next after last bit offset */
  ssize_t nleft; /* Number of bits left in this stream */
  uint32_t accum;
  const uint8_t* buf;

  if (nbits < 0) return -1;

  nleft = pd->nbits - pd->nboff;
  if (nbits > nleft) {
    int32_t tailv, vhead;
    if (!pd->refill || nbits > 31) return -1;
    /* Accumulate unused bytes before refill */
    ASN_DEBUG("Obtain the rest %d bits (want %d)", (int) nleft, (int) nbits);
    tailv = asn_get_few_bits(pd, nleft);
    if (tailv < 0) return -1;
    /* Refill (replace pd contents with new data) */
    if (pd->refill(pd)) return -1;
    nbits -= nleft;
    vhead = asn_get_few_bits(pd, nbits);
    /* Combine the rest of previous pd with the head of new one */
    tailv = (tailv << nbits) | vhead; /* Could == -1 */
    return tailv;
  }

  /*
   * Normalize position indicator.
   */
  if (pd->nboff >= 8) {
    pd->buffer += (pd->nboff >> 3);
    pd->nbits -= (pd->nboff & ~0x07);
    pd->nboff &= 0x07;
  }
  pd->moved += nbits;
  pd->nboff += nbits;
  off = pd->nboff;
  buf = pd->buffer;

  /*
   * Extract specified number of bits.
   */
  if (off <= 8)
    accum = nbits ? (buf[0]) >> (8 - off) : 0;
  else if (off <= 16)
    accum = ((buf[0] << 8) + buf[1]) >> (16 - off);
  else if (off <= 24)
    accum = ((buf[0] << 16) + (buf[1] << 8) + buf[2]) >> (24 - off);
  else if (off <= 31)
    accum = (((uint32_t) buf[0] << 24) + (buf[1] << 16) + (buf[2] << 8) +
             (buf[3])) >>
            (32 - off);
  else if (nbits <= 31) {
    asn_bit_data_t tpd = *pd;
    /* Here are we with our 31-bits limit plus 1..7 bits offset. */
    asn_get_undo(&tpd, nbits);
    /* The number of available bits in the stream allow
     * for the following operations to take place without
     * invoking the ->refill() function */
    accum = asn_get_few_bits(&tpd, nbits - 24) << 24;
    accum |= asn_get_few_bits(&tpd, 24);
  } else {
    asn_get_undo(pd, nbits);
    return -1;
  }

  accum &= (((uint32_t) 1 << nbits) - 1);

  ASN_DEBUG(
      "  [PER got %2d<=%2d bits => span %d %+ld[%d..%d]:%02x (%d) => 0x%x]",
      (int) nbits, (int) nleft, (int) pd->moved, (((long) pd->buffer) & 0xf),
      (int) pd->nboff, (int) pd->nbits,
      ((pd->buffer != NULL) ? pd->buffer[0] : 0), (int) (pd->nbits - pd->nboff),
      (int) accum);

  return accum;
}

/*
 * Extract a large number of bits from the specified PER data pointer.
 */
int asn_get_many_bits(
    asn_bit_data_t* pd, uint8_t* dst, int alright, int nbits) {
  int32_t value;

  if (alright && (nbits & 7)) {
    /* Perform right alignment of a first few bits */
    value = asn_get_few_bits(pd, nbits & 0x07);
    if (value < 0) return -1;
    *dst++ = value; /* value is already right-aligned */
    nbits &= ~7;
  }

  while (nbits) {
    if (nbits >= 24) {
      value = asn_get_few_bits(pd, 24);
      if (value < 0) return -1;
      *(dst++) = value >> 16;
      *(dst++) = value >> 8;
      *(dst++) = value;
      nbits -= 24;
    } else {
      value = asn_get_few_bits(pd, nbits);
      if (value < 0) return -1;
      if (nbits & 7) { /* implies left alignment */
        value <<= 8 - (nbits & 7), nbits += 8 - (nbits & 7);
        if (nbits > 24) *dst++ = value >> 24;
      }
      if (nbits > 16) *dst++ = value >> 16;
      if (nbits > 8) *dst++ = value >> 8;
      *dst++ = value;
      break;
    }
  }

  return 0;
}

/*
 * Put a small number of bits (<= 31).
 */
int asn_put_few_bits(asn_bit_outp_t* po, uint32_t bits, int obits) {
  size_t off;  /* Next after last bit offset */
  size_t omsk; /* Existing last byte meaningful bits mask */
  uint8_t* buf;

  if (obits <= 0 || obits >= 32) return obits ? -1 : 0;

  ASN_DEBUG(
      "[PER put %d bits %x to %p+%d bits]", obits, (int) bits,
      (void*) po->buffer, (int) po->nboff);

  /*
   * Normalize position indicator.
   */
  if (po->nboff >= 8) {
    po->buffer += (po->nboff >> 3);
    po->nbits -= (po->nboff & ~0x07);
    po->nboff &= 0x07;
  }

  /*
   * Flush whole-bytes output, if necessary.
   */
  if (po->nboff + obits > po->nbits) {
    size_t complete_bytes;
    if (!po->buffer) po->buffer = po->tmpspace;
    complete_bytes = (po->buffer - po->tmpspace);
    ASN_DEBUG(
        "[PER output %ld complete + %ld]", (long) complete_bytes,
        (long) po->flushed_bytes);
    if (po->output(po->tmpspace, complete_bytes, po->op_key) < 0) return -1;
    if (po->nboff) po->tmpspace[0] = po->buffer[0];
    po->buffer = po->tmpspace;
    po->nbits  = 8 * sizeof(po->tmpspace);
    po->flushed_bytes += complete_bytes;
  }

  /*
   * Now, due to sizeof(tmpspace), we are guaranteed large enough space.
   */
  buf  = po->buffer;
  omsk = ~((1 << (8 - po->nboff)) - 1);
  off  = (po->nboff + obits);

  /* Clear data of debris before meaningful bits */
  bits &= (((uint32_t) 1 << obits) - 1);

  ASN_DEBUG(
      "[PER out %d %u/%x (t=%d,o=%d) %x&%x=%x]", obits, (int) bits, (int) bits,
      (int) po->nboff, (int) off, buf[0], (int) (omsk & 0xff),
      (int) (buf[0] & omsk));

  if (off <= 8) /* Completely within 1 byte */
    po->nboff = off, bits <<= (8 - off), buf[0] = (buf[0] & omsk) | bits;
  else if (off <= 16)
    po->nboff = off, bits <<= (16 - off),
    buf[0] = (buf[0] & omsk) | (bits >> 8), buf[1] = bits;
  else if (off <= 24)
    po->nboff = off, bits <<= (24 - off),
    buf[0] = (buf[0] & omsk) | (bits >> 16), buf[1] = bits >> 8, buf[2] = bits;
  else if (off <= 31)
    po->nboff = off, bits <<= (32 - off),
    buf[0] = (buf[0] & omsk) | (bits >> 24), buf[1] = bits >> 16,
    buf[2] = bits >> 8, buf[3] = bits;
  else {
    if (asn_put_few_bits(po, bits >> (obits - 24), 24)) return -1;
    if (asn_put_few_bits(po, bits, obits - 24)) return -1;
  }

  ASN_DEBUG(
      "[PER out %u/%x => %02x buf+%ld]", (int) bits, (int) bits, buf[0],
      (long) (po->buffer - po->tmpspace));

  return 0;
}

/*
 * Output a large number of bits.
 */
int asn_put_many_bits(asn_bit_outp_t* po, const uint8_t* src, int nbits) {
  while (nbits) {
    uint32_t value;

    if (nbits >= 24) {
      value = (src[0] << 16) | (src[1] << 8) | src[2];
      src += 3;
      nbits -= 24;
      if (asn_put_few_bits(po, value, 24)) return -1;
    } else {
      value = src[0];
      if (nbits > 8) value = (value << 8) | src[1];
      if (nbits > 16) value = (value << 8) | src[2];
      if (nbits & 0x07) value >>= (8 - (nbits & 0x07));
      if (asn_put_few_bits(po, value, nbits)) return -1;
      break;
    }
  }

  return 0;
}

int asn_put_aligned_flush(asn_bit_outp_t* po) {
  uint32_t unused_bits = (0x7 & (8 - (po->nboff & 0x07)));
  size_t complete_bytes =
      (po->buffer ? po->buffer - po->tmpspace : 0) + ((po->nboff + 7) >> 3);

  if (unused_bits) {
    po->buffer[po->nboff >> 3] &= ~0u << unused_bits;
  }

  if (po->output(po->tmpspace, complete_bytes, po->op_key) < 0) {
    return -1;
  } else {
    po->buffer = po->tmpspace;
    po->nboff  = 0;
    po->nbits  = 8 * sizeof(po->tmpspace);
    po->flushed_bytes += complete_bytes;
    return 0;
  }
}
